Manufacture of elastic products with a textile basis



Patented Apr. 11, 1939 PATEN'i orrlcs MANUFACTURE OF ELASTIC PRODUQ'ES WITH A TEXTILE BASIS Lon Sylvain Max Lejeune, Paris, and Emile Jean Albert Lejeune, Lille, France, assignors, by mesne assignments, to Hevaloid Corporation, Dover, Del a corporation of Delaware No Drawing. Application September 2, 1936, Se-

rial No. 99,149. In France April 5, 1933 22 Claims.

Our present application has for its object the manufacture of new elastic products with a textile basis and is a continuation-impart application of our prior application, Serial No. 690,760, filed September 23, 1933.

The invention relates more particularly to the manufacture of elastic textile fabrics, that is to say, products of every variety that have a textile basis, impregnated or associated'with an elastic or plastic substance such as rubber. The invention comprises the improved elastic fabrics themselves and also the herein described process of making the same. Its main object is to obtain fabrics (including the linear elements whereof they are composed) which possess the qualities of strength and elasticity in a very high degree, together with relatively high transverse compressibility, and to obtain such products by a process which is even more economical than the,

processes whereby the highest grades of elastic textile fabrics are now produced. The elastic textile products obtained by the process herein described, and which are included within the present invention, are characterized and distinguished from other commercial products of the same class chieflyby the following characteristics: first, a relatively high degree of tensile strength; second, a relatively high degree of residual elasticity, that is to say, of elasticity which remains after the properties of the fabric have been permanently fixed; third, a physical union of the basic textile fabric and the rubber which is so close and tenacious as to amount to virtual homogeneity, this being a very distinctive and 4, conspicuous characteristic of the new products;

fourth, at relatively high degree of transverse compressibility; fifth, a thorough impregnation with rubber or the like which can be made to penetrate to all parts of the fibrous mass.

The invention specially contemplates the employment of cotton fibers, but can be successfully applied, to other textiles, such as jute, flax, hemp, ramle, etc. It is to beunderstcod that where "rubber is mentioned. herein, other elastic or plastic substances suitablefor the purposes of the invention are included within the meaning of the word. a

The process whereby fabricsand linear elements having the above and other desirableproperties are obtained'according to the invention is characterized mainly by the initial step or operation, according to which the primary fibrous elements (rovings) constituting the textile base are subjected to what is herein termed an inverse twist, whereby said rovings are formed into ele- 5 ments having novel and distinctive characteristics. The ultimate fabric or product is made of these linear elements. Said linear elements may be formed of commercial rovings of any of the grades (or degrees of initial twist) that are 10 readily obtainable. The first step in the inverse twist operation is to take two (or more) rovings and impart to each individually such a supertwist (inv the same direction as its primary twist) that they can no more readily be drawn out substantially, for example, in the case of rovings of size, 2.5 (French nomenclature) until the total twist aggregates, say, 200 turns per meter, more or less. Obviously, if rovings are obtainable which have already been given a suficiently high 6 degree of twist, which varieswithin somewhat wide limits according to the ultimate product sought and to other variable conditions, the specified over-twist will not be required. Two or more such fibrous units, each twisted in the same direction and'to thepredetermined degree, are brought together and are twisted as an assembly in the opposite direction to that in which the individual rovings were twisted. The best result is obtainedwhen this reverse twist approximates 3 the same number of turns as the total initial twist imparted to the individual units of the linear elements; for then the textile elements will be found to be in a state of approximate equilibrium, that is, a state wherein the element has little or no tendency to untwlst.

As has already been stated, the amount of twist given to the individual rovings in the first instance and then given to the assembled rcvings in the reverse direction depends upon several 40 variable conditions, but it is easy to ascertain in each particular case what amount of twist, that is, the number of turns per linear unit, should be 1 given in each direction. It has been found that particularly good-results are obtained with linear elements each composed of two cotton rovings of size No. 2.5, and to which a total twist of 200 turns per meter in each direction has been given. If, 'for example, the initial ordinary twisting of the roving was 80 turns, a supplemental twisting of 120 turns would be required to make the desired total. As is known, when a. cotton roving of size No. 2.5 has been given a twist of approximately 200 turns per meter, it cannot be substantially drawn out. Therefore, it suifices, in order to give a sufliciently definite idea. of the amount of twist that should be imparted to the rovings, to state that the advantages of the invention will be realized in a satisfactory degree when the rovlngs are twisted, before being assembled, to such an extent that they cannot be substantially drawn out. A linear element so made is found to possess, contrary'to what would be expected, a higher degree of tensile strength than the sum of the tensile strength of the several units. Such a linear element, when treated according to this invention as will be explained hereafter, is found to possess extraordinary degrees both of strength and elasticity. And when it is impregnated with rubber or the like, the resulting elastic products approach much closer than any now obtainable the ideals setforth above.

The linear elements themselves (the direct products of the inverse twist) are specially characterized by structural uniformity as regards the arrangement of the fibers composing each of the fibrous units relatively to each other, in consequence of which each unit is in a state of approximately uniform openness throughout and hence is readily permeated even to the center by the swelling agent. Moreover, this structural openness remains after the treatment according to the invention, so thatthe element is readily permeable even to the center by the elastic substance in solution or suspension. During the imparting of the reverse twist to the assembly of supertwisted rovings each unit undergoes a compound movement: first, there is the movement whereby the several units are twisted into an inversely twisted element, in the course of which they rotate on a common axis, each unit revolving around the other; second, there is the movement whereby the fibrils of each unit are rotated with reference to each other in a direction opposite to the twist initially imparted to them, the result being a rearrangement of the constituent fibrils relatively to each other and also a substantial relaxation of the strong centripetal compression exerted by the outer fibrous helices of the unit resulting from the initial twist. Thus is brought about a unique structural condition of the textile linear element as a whole, which condition is conducive to the most favourable results from the successive steps of treatment and impregnation.

The treatment to which are subjected the textile elements according to the invention essen-' tially consists in a treatment without tension by means of a contracting and swelling agent such as caustic soda lye, in conditions such that the linear element have their fibres strongly contracted and swollen without however being subjected to substantial mutual compression.

In contrast with what has been heretofore effected when textile fabrics or elements have been treated with hydrolyzing agents (in which case the elasticity of the product is merely that of the fiber proper and the tensile strength is that of the impregnating material) the process of the present invention effects a re-arrangement of the swollen and contracted fibers such as to form a very open texture, while there is nevertheless a certain twisting, or a particular path of individual fibers which is equivalent to a twist, with a consequent bonding together and interlocking of the fibers without diminution of the elasticity, but on the contrary with an enhancement both of the elasticity and also of the tensile strength of the textile base. In consequence of the rearrangement of the individual fibers with respect to each other and of the contracting and swelling effect resulting from the action of the soda lye or the like, and also of the additional elasticity imparted by the impregnating substance, the elasticity of the linear elements themselves and therefore that of webs or fabrics composed thereof, is much greater than that of the fiber itself or of a thread which has not been subjected to the described inverse twist and the subsequent swelling and contracting treatment.

The particular agent whereby the contraction and distention of the inversely twisted linear elements is to be effected will be selected according to the particular product in view, preference being given to agents, acid or alkaline as the case may be, that will produce a maximum, and as nearly as possible, a homogeneous swelling and shortening effect; and to agents that do not cause deterioration of the fiber. Agents which transform the fiber without deterioration into hydrocellulose may be used with advantage. The best results thus far have been obtained with vegetable fibers by the use of alkalis, especially soda, under proper conditions of concentration, temperature, and duration of treatment.

This treatment yields a swollen and contracted linear element in which the fibers are not appre-' How-' ciably compressed one against the other. ever, the reciprocal interlocking of the fibers is sufiiciently increased by the treatment to add substantially to the tensile strength of the ele-i ment. The elasticity 'also is considerably increased, not only by reason of the transformation of the substance of the fiber into one that is more elastic, but also by reason of the condition into which the linear element as a whole has been brought. Furthermore, the residual elasticity of an inversely twisted linear element so treated, that is to say, the elasticity which exists after a tension produced by a force exceeding that which produces the first permanent elongation, is greatly augmented.

In carrying out the contracting and swelling treatment according to the invention, it may be useful to employ a wetting agent, in order that the textile elements be fully wetted by the bath in which they are immersed. As wetting agent there may be employed any wetting agent which is commonly known for the usual treatments of textiles with liquids.

The textile elements or textile products are allowed to remain in the bath under conditions such as will be more fully described in relation with the examples given hereafter; afterwards the textile is extracted from the bath and is expressed so that the greatest part of the bath may be recovered.

The steps of the process which follow the inverse twist operation'may be performed in either of several different sequences. It might seem that the logical order of procedure in making an elastic fabric would ,be to subject the inversely twisted linear element first to the action of the contracting and swelling agent and then to impregnation with the selected elastic or plastic substance, and then (either before or after vulcanization) to weave said element into a fabric; and this order of procedure may be adopted with satisfactory results. Preferably, however, the

Team: I

Concentration: 30 B.; temp. 18 C'.; duration 15 minutes 0 Raw Scalded Tensile Elongation Tensile Elongation trength at breaking trength at breaking in kg point in kg. point Percent Percent 7. 350 23. 76 8.500 20.00 7. 250 22. 8. 400 25. 75 7. 700 25.00 8. 950 28. 50 t 7. 300 25.00 8. 950 20. 50 7. 400 23.00 8. 300 27.00

Mean Mean Mean Mean Weight 520 grams per 1,000 meters, fibers not tensloned.

TABLE II Concentration: 20 B.; temp. 8 C'.; duration 30 minutes Raw Scalded Tensile Elongation Tensile Elongation strength at breaking strength at breaking in kg. point in kg. point Percent Percent 7. 600 22. 0 8. 600 31. 00 7. 650 23. 0 8. 750 29. 00 7. 500 23. 5 8. 300 28. 75 7. 600 23. 5 8. 300 29. 75 7. 650 23. 0 8. 700 28.00

Mean Mean Mean Mean Weight 520 grams per 1,000 meters, fibers not tensioned.

TABLE III Before treatment with soda Raw Scalded Tensile Elongation Tensile Elongation strength at breaking strength at b eaking in kg. point in kg. point Percent Percent 5 0 5. 600 10.8

Third example.--Taking two rovings of cotton of total weight 380 mg. per meter; twisting them 140 turns per meter to the right, then, after assembly, 140 turns to the left, and treating them as stated above, a thread weighing 500 grams per 1000 meters is obtained, the longitudinal contraction in the treatment having been 30%, while the initial tensile strength of the original thread, twisted 140 turns, was 6.2 kg. and the elasticity 10%. This treated element has a tensile strength of 9.5 kg. and an elasticity of 36%.

In comparison, an ordinary cord of the same material, also weighing 500 grams per 1000 meters, comprising an assembly of fifteen No. 18 threads, a spinning twist of 800 turns, a. twisting torsion of 690 turns in the same direction, and a cording twist of 350 turns, was found to possess the following characteristics: Tensile strength-7.50O kgs.; elongation at breaking point24%; threads very tightly squeezed together.

With jute, treated as described above, an elasticity of 25% was obtained; whereas this fiber, as is well known, has only 3% elasticity in its natural state and is in consequence very brittle.

With respect to the treatment which is carried out subsequently to the contracting and swelling treatment just above described, as before said, the'textile fabric-assuming that linear elements woven into a fabric are contemplated-remains in the bath during the time above indicated. Afterwards the fabric is extracted from the bath and expressed so as to recover as much as possible of the said bath.

The fabric is then carefully washed, and then submitted to the treatment of boiling. Said boiling is performed under the ordinary conditions of such well-known operation, 1. e. by means of a lye of cabonate of soda of 3%, to which there is added a soda soap of 1,5% under a pressure of 1.5 atm. corresponding to a temperature of 113 C. for 4 hours. The percentage always is calculated with respect to the weight of dry cotton.

After having been boiled, the fabric is washed with warm water at for about 1 hour, carefully washed with cold water, neutralized through a solution of trade hydrochloric acid of 0.5 B., then again washed till the chlorides are eliminated. Finally the treated fabric is carefully dried so that there only remains about 7% of wetness with respect to the weight of the dry cotton. The fabric is then ready for impregnation.

Instead of making with the so called inverse twists a fabric which is subjected to a swelling and contacting operation by means of a swelling and contracting agent, such as soda lye according to the hereabove described process, further subjecting the said fabric to a boiling treatment such as a treatment by a diluted soda carbonate lye under pressure at an increased temperature during several hoursdzhe fabric being thenwashed, eventually dried and impregnated with elastic or plastic material, the inverse twists may be first subjected to the aforesaid swelling and contracting treatment, then woven in the form of a more or less closed mesh fabric and the so formed fabric is then subjected to a boiling treatment such as the above mentioned boiling teatment, then washed, eventually dried and impregnated with elastic or plastic material.

The linear elem treated as described, may be made to take up an amount of rubber equal in weight to or more than that of the fabric itself by simple impregnation without repetition.

Impregnation with elastic or plastic substance The effect of the inverse twist and the swelling and contracting treatment is to bring the textile fabric or element as a whole and its component fibers individually into a condition that is very favorable to complete and thorough impregnation with rubber or other elastic or plastic substance; insomuch that the desired result can be obtained'without the aid of costly vacuum and pressure appliances and operations such as have been heretofore used to complete penetration of the fibrous mass by the rubber or like material.

An important object of the impregnation operation is to fix permanently the properties of strength and elasticity that have been imparted to the fabrics or linear elements by the oper-,

ations of inverse twisting and of swelling and contraction.

For the purpose of the impregnation operation, use may be made of a natural or synthetic susts or fabrics, previously The impregnating liquid may be applied by 5 means of brushes or in a calendering machine,

or preferably by soaking. Vacuum or pressure, or both, may if desired be used in special cases to aid the impregnation; but, as already stated, those aids are not needed in order to obtain the benefits of the invention.

When a solution is used for'the impregnation, it is necessary, of course, to dry the element previously; but when latex or analogous natural or artificial suspension is used, drying is not necessary.

Preferably the impregnation is carried out by immersion of the textile product in a bath of latex, containing for example 40% of dry rubber together with the vulcanising products. The impregnation occurs, preferably without vacuum or pressure being applied, in vats or other receptacles which are closed with a cover which is sufficiently tight to prevent the ammonia from evaporating, which latter would result in a coagulation of the surface of the bath. After each impregnating operation, the ammonia content of the bath is brought to the required degree by adding thereto a solution of trade ammonia.

The degree of impregnation desired will determine the duration of the treatment. ,Latex, natural or concentrated and preferably containing all elements necessary for vulcanization, is specially suitable.

After the impregnation, the fabric or other textile product, is placed in conditions suitable for coagulating of the rubber. To effect this, the ammonia is allowed to evaporate or is neutralized.

When the coagulation is eflected, the impregnated textile product, e. g. fabric, is placed in such conditions that the water still contained therein evaporates for the greater part. To effect this, the fabric or the like can be calendered with an usual calender so as to remove the greatest possible partof water, afterwards the product is dried in any suitable manner. Care shall be taken that the temperature of the drying apparatus be lowered as the fabric dries.

The quantity of water remaining at that time in the textile fabric or product will not exceed w 4% of the weight of the impregnated fabric.

In most cases, the impregnating treatment of the final impregnated products to be obtained is followed by a vulcanization. The fabric when impregnated are preserved until it is desired to '5 vulcanize the same. For this purpose they are kept preferably in warehouses which are dimly lighted and not too moist. When it is desired to obtain fabrics composedoi? several plies or thicknesses, the component plies are to be stuck together prior to warehousing in order to prevent oxidation of the surfaces of the plies.

The impregnated inverse twisted linear elements or fabrics made therefrom may be stretched (before or after drying but in all cases before vulcanization) for the purpose of diminishing their residual elasticity, which stretching which it is not desired (as in the transverse direction of a belt) but also thereby surface area that has been lost through shrinkage may be regained. In the case of a very elastic fabric the initial lengthier width) may be exceeded and the dimension thus attained may be fixed.

The product is vulcanized preferably under a pressure of about 25/30 kg. per cm The invention also comprises means for preventing any substantial bulging or warping of the fabric due to the fact that the selvages of the same are always more compressed than the rest of the fabric. In order to avoid any risk of such bulging, it is preferred, before the operation of stretching and vulcanization, to cut the selvages of the fabric in such a manner that the strips or sheets finally obtained are prevented from bulging. As aforesaid, the removal of the selvages by cutting should take place before the fabric is stretched.

In the tables below are given the practical results of the impregnation by rubber latex of linear elements corresponding to those of Tables I and II above. The rubberizing waseffected by immersion in natural latex for'four hours, followed by a coagulation with acetic acid, drying and vulcanization.

Impregnation of elements treated as per Table I,

Raw Scalded Tensile Elongation Tenslle' Elongation strength at breaking strength at breaking in kg. point in kg. point Percent Percent 8.700 20.00 0. 3 22. 8. 850 20. 50 8. 700 22. 00 8. 400 21. 00 8. 750 22. 50 9.000 20.00 8. 650 21.00 8. 500 %).00 9.000 21. 50

Mean Mean Mean Mean Impregnation ofelements treated as per Table II, supra Raw Scalded Tensile Elongation Tensile Elongation strength at breaking strength at breaking in g point in kg. point Percent Percent 8. 950 19. 60 9. 100 10. 75 8.800 18.00 8.350 19.00 8. 800 18. 25 9. 200 10. 00 8. 250 18. 50 8. 900 19. 00 8. 750 10. 00 8. 650 19. 00

Mean Mean Mean Mean The above tables show that, starting with an inversely twisted linear element weighing 520 grams per 1000 meters and having a tensile strength of 7.5 kilograms to 9 kilograms, with an elongation at breaking point of 24-30%, and impregnating it with rubber latex to 18% of its initial weight, one obtains a rubberized textile thread having a tensile strength of 9 kilograms, with an elongation of 20-23% and a residual longitudinal elasticity which varies from to 5.5% under a tension of 4.5 kilograms. This residual longitudinal elasticity is superior by 20% to that of the non-impregnated twist.

Thus it will be noted that the tensile strength and the elongation (especially the latter) of such an impregnated inverse twist are considerably higher than those of an impregnated cord, for the same weight of the same textile material and the same impregnating substance. These differences arise from the fact that, owing to the structure of the ordinary cords they can be only superficially impregnated, from which it results that the fibers of those cords are subject to varying operating conditions, according to whether or not they are in the outer zone which is reached by the impregnating liquid. In the impregnated textiles of the present invention, on the contrary, the elongation is not produced by the sliding of the fibers relatively to each other, but by the stretching of the fibers themselves. On the other hand, because of the peculiar arrangement of the fibers relatively to one another and the absence of compression, the straightening of the fibers is less hindered than in an ordinary impregnated cord. Moreover, the homogeneity of the product of the present invention is such that all the fibers undergo stress or strain simultaneously to approximately the same extent. The increase of strength is due largely to this cause.

The products of the above described process can be readily distinguished by their observable characteristics and properties from products of the same class hitherto known. The inversely twisted linear element itself, which is an intermediate product, has distinctive characteristics whereby it can be identified. It imparts those distinctive characteristics to the final products of which it forms the textile basis. Said linear element is specially characterized in that while the textile units composing it are twisted together, they are individually in such condition of openness that the constituent fibers lie close together without reciprocal gompression, there being practically no centripetal pressure exerted by the fibers upon others nearer the center, and practically no reciprocal pressure exerted by the rovings upon each other. Consequently the linear element as a whole is in a state of approximately uniform openness to penetration by the swell ing and contracting agent and by the rubber dispersion or solution. Penetration by the rubher is promoted also by the structure of the outer and inner surfaces of the fibers themselves. The

fibers of the element are also, as the result of the inverse twist, found in the form of helices and in such a condition, that when a tensile longitudinal stress is exerted upon the element the fibers are all straightened substantially to the same extent and are tightened together and are all subjected to the same stress. This peculiar structural condition, which is readily observable under a magnifying glass of moderate power, is the principal cause of the valuable properties, already described, of the final products of this invention-such as their great tensile strength. their high coefllcient of residual elasticity, and of transversal compressibility, the large proportion of rubber incorporated in the textile, and the remarkably tenacious cohesion of the rubber and the fibers. This cohesion is such as to integrate the two constituents, forming what is, for all practical purposes, a homogeneous product.

It is to be understood that the fabrics made according to the present invention comprise all kinds of woven fabrics, knitted fabrics or cord I fabrics and that they can be used for manufacturing all products or articles in which impregnated textiles are used.

What we claim is:

1. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings in the same direction, bringing together the twisted units, twisting the assembled units in the direction opposite to that in which the individual units were twisted until an appreciably opened linear element is obtained, and treating without substantial tension the linear element so formed with a contracting and swelling agent.

2. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings in the same direction, bringing together the twisted rovings, twisting the assembled units in the direction opposite to that in which the individual units were twisted until an appreciably opened linear element is obtained, weaving a number of linear elements so formed into a fabric, and treating the fabric without substantial tension with a contracting and swelling agent.

3. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings in the same direction, bringing together the twisted rovings, twisting the assembled units in the direction opposite to that into a fabric, treating the fabric without substantial tension with a contracting and swelling agent, and impregnating the fabric with rubber.

4. In the process of claim 3, the removal of a part of the elasticity of the linear element by tension and fixing the degree of elasticity thus attained by vulcanisation.

5. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings' in the same direction, bringing together the twisted units, twisting the assembled units in the direction opposite to that in which the individual units were twisted until the number of turns of the reverse twist equals approximately that of the previous twist of the individual units, and treating without substantial tension the linear element so formed with a contracting and swelling agent.

6. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings in the same direction. bringing together the twisted rovings, twisting the assembled units in the direction opposite to that in which the individual units were twisted until the number of turns of the reverse twist equals approximately that of the previous twist of the individual units, weaving a number of linear elements so formed into a fabric, and treating the fabric without substantial tension with a contracting and swelling agent.

7. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rcvings in the same direction, bringing together the twisted rovings, twisting the assembled units in the direction opposite to that in which the individual units were twisted until the number of turns of the reverse twist equals approximately that of the previous twist of the individual units, weaving a number oi linear elements so formed into a fabric, treating the fabric without substantial tension with a condistributed throughout the fibrous mass and firmly united to the individual fibers.

9. An elastic product having atextile basis composed of linear elements, each comprising a plurality of supertwisted rovings firmly twisted together in the direction opposite to that of the twist of the said rovings, the individual units being in a state of uniform openness to penetration by liquids and of absence of internal compression, the constituent fibers being an assemblage of helices having approximately the same pitch.-

10. A woven fabric formed of linear textile elements comprising each a plurality of supertwisted rovings twisted together in the direction opposite to that of the twist of the said rovings,

. the individual units being in a state of uniform openness to penetration by liquids and without reciprocal compression between the constituent fibers, said elements being impregnated with an elastic substance which fills the interstices between them and binds the fibers into a dense bringing together the twisted units, twisting the.

assembled units in the direction opposite to that in which the individual units were twisted until an appreciably opened linear element is obtained, and treating without substantial tension the linear element so formed with a contracting and swelling agent added with a wetting agent, subjecting then the linear element to a boiling treatment, to washing and drying.

13. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings in the same direction, bringing together the twisted rovings, twisting the as sembled units in the direction opposite to that in which the individual units were twisted until an appreciably opened linear element is obtained, weaving a number of linear elements so formed into a fabric and treating the fabric without substantial tension with a bath formed of a contracting and swelling agent and added with a,

wetting agent, subjecting then the fabric to a boiling treatment and then to washing and dryingr 4 14. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings in the same direction, bringing together the twisted rovings, twisting the assembled units in the direction opposite to that I in which the indivldual, units were' twisted until an appreciably opened linear element is obtained weaving a number-of linear elements so formed into a fabric, treating the fabric without substantial tension with a contracting and swelling agent added with a. wetting agent, subjecting then the fabric to a treatment of boiling, then to washing and drying, and impregnating the treated fabric. with elastic material.

15. Process for the manufacture of elastic textile products, which'comprises twisting each of a plurality of rovings in the same direction, bring- .ing together the twisted rovings, twisting the assembled units in the direction opp s te to that I in which the individual units were twisted until into a fabric, treating the fabric without substantial tension with a contracting and swelling agent added with a wetting agent, subjecting then the fabric to a treatment of boiling, then to washing and drying, impregnating the treated fabric with elastic material, allowing the same to coagulate and then to dry, stretching the linear elements to remove part of the elasticity thereof and fixing the degree of elasticity thus attained by vulcanization.

16. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings in the same direction, bringing together the twisted units, twisting the assembled units in the direction opposite to that in which the individual units were twisted until the number of turns of the reverse twist equals approximately that of the previous twist of the individual' units, treating without substantial tension the linear elements so formed with a contracting and swelling agent added with a wetting agent, subjecting then the linear elements to a boiling treatment, then to washing and drying.

17. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings in the same direction, bringing together the twisted rovings, twisting the assembled-units in the direction opposite to that in which the, individual units were twisted until the number of turns of the reverse twist equals approximately that of the previous twist of the individual units, weaving a number of linear elements so formed into a fabric, treating the fabric without substantial tension with a bath formed of a contracting and swelling agent and added with a wetting agent, subjecting then the fabric to a treatment of boiling and then to washing and drying.

18. Process for the manufacture of elastic textile products, which comprises twisting each of a plurality of rovings in the same direction, bringing together the twisted rovings, twisting the assembled units in the direction opposite to that in which the individual units were twisted until the numberof turns of the reverse twist equals approximately that of the previous twist of the individual units, weaving. a number of linear elements so formed into a fabric, treating the fabric without substantial tension with a contracting and swelling agent added with a wetting agent, subjecting then the fabric to a boiling treatment, then to washing and drying and impregnatlng the fabric with an elastic material.

' 19. Process for the manufacture of elastic textile products, which comprisestwisting each of a plurality of rovings in the same direction, bringing together the twisted rovings, twisting the assembled units in the direction opposite to that in which the individual units were twisted until the number of'turns of the reverse twist equals approximately that of the previous twist of the individual units, weaving a number of linear elements so formed into a fabric,- treating the fabric without substantial tension with a contracting and swelling agent added with a wetting agent, subjecting then the fabric to a boiling treatment, then to washing and drying, impregnating the fabric with an elastic material, coagulating the same and drying it, cutting the selvages of the fabric and subjecting the said fabric to stretching and vulcanization.

20. A linear textile element comprising two rovings of French size No. 2.5 which have been twisted individually in the same direction for about 200 turns and are twisted together in the opposite direction also for about 200 turns the two individual rovings of the assembly being in a state of uniform openness to penetration by liquids and without reciprocal compression between the constituent fibers, said fibers being contracted and swollen as well as boiled.

21. A woven fabric formed of linear textile elements comprising each two rovings' of French size No. 2.5 supertwisted up to about 200 turns and twisted together in the direction opposite to that of the twist of the said rovings also for about 200 turns, the two individual units being in a state of uniform openness to penetration by liquids and without reciprocal compression between the constituent flbers, said elements being impregnated with an elastic substance which fills the interstices between them and binds the fibers into a dense and strongly coherent fabric.

22. An elastic product having a textile basis formed of linear elements each comprising two rovings of Frenchsize No. 2.5 which have been twisted individually in the same direction for about 200 turns and aggregately in the opposite direction also for about 200 turns and 0! rubber uniformly distributed throughout the fibrous mass and firmly united to the individual fibers.

LEON SYLVAIN a. LEJEUNE. EMILE JEAN ALBERT LEJEUNE. 

